Edge Blending with Modul8 Demystified:
http://youtu.be/6Wt1GmOopVo
Be sure to watch through flash because I update the annotations. This method doesn't work with all colors/media.
I use a high res gradient mask file along with the Mask (Global) module to blend the edges. By adjusting the scale/ratio of the mask, I can change the width/shape of the blend and dial it in for the screen overlap. It's basically just two layers playing the same movie, each cropped through Crop Layer (udart) so they only show one "projectors" worth of movie and therefore when played in snyc you only get overlap on the edge, which you then blend out.
The files are here:
http://bearslooptasticspectacular.com/edgeblending/
I used an easycap to go s-video from my DVR into SP>Video Input #1 and now I watch satellite tv on my 20 foot screen, in my 400 square foot studio apartment.
Hope that helps!